Recently in the interest of pollution control the Federal Government has issued regulations for the design and performance of sanitary equipment, specifically, marine toilets aboard commercial and pleasure craft of all kinds. In design the equipment is of the thru flow type as opposed to holding tank systems formerly used to provide for chemical treatment before the discharge or to hold the effluent until such time as the vessel can discharge into a dockside receiving facility. For such flow thru equipment the regulations are that the effluent be treated on the way from the toilet to the overboard discharge line in such a way as to render the coliform count to not more than 240 per 100 milliliters. The apparatus herein disclosed is designed to replace holding tanks in such vessels as still have such equipment aboard and to be interposed between the toilet and the overboard line in such vessels as have direct discharge without holding tanks to enable rendering the effluent flushed from a manually operated or electrically operated toilet within the limits imposed by the recently adopted regulations, and further, to provide equipment for this purpose which can be easily installed, is not influenced by the motion of the vessel and/or vibrations, is automatically rendered inoperative in the absence of chemicals employed for the treatment, requires a very low source of electric power for its operation and is relatively inexpensive.